The BBC apologized today after US rock band Rage Against the Machine - battling with The X -Factor winner Joe McElderry to be the Christmas No 1 - turned the airwaves blue on the Radio 5 Live breakfast show.

Rage Against The Machine were guests on the morning show, hosted by Nicky Campbell and Shelagh Fogarty, and invited to play a live version of their song, Killing in the Name.

The band had been asked not to sing the final refrain, "Fuck you, I won't do what you tell me!" but singer Zack de la Rocha sang it anyway.

It was not until the fourth repetition that the breakfast show production team faded out the microphone and returned to the studio.

"Get rid of it!" Fogarty could be heard shouting in the background. "Sorry, we needed to get rid of that because that suddenly turned into something we weren't expecting," she told listeners. "Well, we were expecting it and we asked them not to do it and they did it anyway."